At night, we hear this metallic thunking, like something is flip-flopping in our radiator. It only happens when the lights are out, and only when we're being quiet. Then, when we indicate our presence, it stops.
There was also a weird rustling, like someone had a bunch of tape and was balling it in their hand. REAL close to the bed.

So, yeah. I'm thinking it's either a mouse or a demon or something.

(Oh, God, I hope it's not a demon. I'm so scared of everything paranormal, even though I'm really interested in it. Ugh...contradictions suck.)